Question

Thực hiện phép tính

a, \(\dfrac{3}{5}\)+\(\dfrac{4}{7}\). \(\dfrac{14}{6}\)

b,\(\dfrac{10}{21}\)-\(\dfrac{3}{8}\).\(\dfrac{4}{15}\)

c, (\(\dfrac{2}{3}\)+\(\dfrac{3}{4}\)).(\(\dfrac{5}{7}\)+\(\dfrac{5}{14}\))

d,\(\dfrac{4}{5}\)+\(\dfrac{3}{5}\):3-\(\dfrac{7}{8}\)

Answer 1

`3/5 + 4/7 . 14/6`

`=3/5 + 4/7 . 7/3`

`=3/5 + (4.7)/(7.3)`

`=3/5 + 4/3`

`=9/15 + 20/15`

`=(9+20)/15`

`=29/15`

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`10/21 - 3/8 . 4/15`

`=10/21 - (3.4)/(8.15)`

`=10/21 - (1.1)/(2.5)`

`=10/21 - 1/10`

`=79/210`

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`(2/3 + 3/4) . (5/7 + 5/14)`

`= ( 8/12 + 9/12) . (10/14 + 5/14)`

\(=\left(\dfrac{8+9}{12}\right).\left(\dfrac{10+5}{14}\right)\)

`=17/12 . 15/14`

`=85/56`

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`4/5 + 3/5 : 3 - 7/8`

`=4/5 + 3/5 xx 1/3 - 7/8`

`=4/5 + 1/5 - 7/8`

`=5/5 - 7/8`

`=1-7/8`

`=8/8-7/8`

`=1/8`